def ceaser_number(str, k):
    ans = ""
    #空数组：保存答案

    for c in str:
        ascii = ord(c)
        ascii += k
    #循环，把每一项都加密好
        
        if ascii > ord('z'):
            ascii %= ord('z')
            ascii += ord('a')
            ascii -= 1
    #特殊情况：是z的话加成a

        ans += chr(ascii)
    #答案数组追加目前项
    
    return ans
    #返回数组答案

print(ceaser_number('iamdaniel', 3))